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Procyan
2010-Aug-09, 09:38 AM
From the 9 August Science and Technology Section of The Hindu about the mock Mars mission currently transpiring in Russia ...
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Charles recently had a birthday, celebrating with his roommates with thawed cake and powdered wine. He even had the luxury of receiving a telephone greeting - in French - from a friend living in Moscow.

“That’s no longer possible,” Graef said.

In the simulation, the spacecraft has travelled too far from Earth to receive voice transmissions. Getting answers from ground controllers takes ever longer for the crew, as radio signals take 20 minutes from Mars to their home planet.
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Question: Why would voice transmissions be unreadable and also how would communications be acheived in a real mission, CW Morse?

slang
2010-Aug-09, 10:23 AM
I don't see how voice transmissions would be impossible. Mars Reconnaissance Orbiter (http://en.wikipedia.org/wiki/Mars_Reconnaissance_Orbiter#Telecommunications_sys tem) is capable of up to 6 megabit per second, and that design is already dated compared to a future manned Mars mission. From personal experience in the 80's I know that voice can be encoded in 2 bits and can still be audible enough to understand words. Figure a 6 KHz or so sampling rate... plenty of bandwidth available to send digitally encoded voice data. Maybe they mean radio communication without digital encryption?

astromark
2010-Aug-09, 10:40 AM
'They' in staging a real a possible mission simulation. Are simply enforcing the fact. That a twenty minute conversation is difficult.

The travel time of the signals regardless of the format. encoding and band width does not make it quicker. Thats not the issue.

Those signals and the distance they need to travel... its all there is to this.

cjameshuff
2010-Aug-09, 11:30 AM
I don't see how voice transmissions would be impossible. Mars Reconnaissance Orbiter (http://en.wikipedia.org/wiki/Mars_Reconnaissance_Orbiter#Telecommunications_sys tem) is capable of up to 6 megabit per second, and that design is already dated compared to a future manned Mars mission. From personal experience in the 80's I know that voice can be encoded in 2 bits and can still be audible enough to understand words. Figure a 6 KHz or so sampling rate... plenty of bandwidth available to send digitally encoded voice data. Maybe they mean radio communication without digital encryption?

Plus, as they travel further away from Earth and the time lag becomes more significant, keeping the transmission at "real-time" rates becomes more and more meaningless. A 30 second response taking a minute to receive isn't a problem when the speed of light means you won't get it until 20 minutes after sending the initial message anyway.

Procyan
2010-Aug-09, 02:09 PM
Oh now I see. Thanks for clearing that up for me. On an actual mission would voice contact be maintained as monologues downloaded for later playback? I would want to hear some actual voice contact from homebase especially that far out.

Procyan
2010-Aug-09, 02:16 PM
"Hey Charles, lets relax and listen to some earth transmissions over a nice glass of powdered wine." Talk about the right stuff :)

Sam5
2010-Aug-09, 04:44 PM
One man in a box. Test, 1959. After only 20 days:

http://www.youtube.com/watch?v=W6ilrUmefL8&feature=related

Procyan
2010-Aug-09, 08:21 PM
Don't go away Mars. We'll be coming for real soon.

Thx Sam :)

Romanus
2010-Aug-09, 10:45 PM
I see. So interplanetary conversations will basically be...vlogs. ;)

mugaliens
2010-Aug-10, 12:07 AM
Oh, joy. Can I play?


Question: Why would voice transmissions be unreadable...

No clue.


...and also how would communications be acheived in a real mission, CW Morse?

E-mail and message forum. Probably vBulletin. What else?